DIY Macro Lens Reverse Mount Extension Tube

A little background, taken from the Macro Wiki.
Placing an extension tube between the camera body and the lens. The tube has no glass in it; its sole purpose is to move the lens farther from the film or digital sensor. The farther the lens is, the closer the focus (and the bigger the magnification). Also, less light will reach the film or sensor, therefore a longer exposure time will be needed. Reversing the lens using a "reversing ring". This special adapter attaches to the filter thread on the front of a lens and makes it possible to attach the lens in reverse. Excellent quality results up to 4x lifesize magnification using fairly cheap, "standard" (not specially designed for macro) lenses can be produced. Magnification ratio is calculated by dividing the focal length of the normally mounted lens by the focal length of the reversed lens (i.e., when a 50 mm lens is reverse mounted on a 200 mm lens a 4:1 magnification ratio is achieved). So having said that let's get it on. Here is what you are going to need, mostly from the plumbing department at your local hardware store.

Materials

2 Inch Couplings. You may only need one or you may need two, depending on the set up you go for.

Epoxy Glue

2 Inch diameter piece of PVC pipe


*note - After completing this tutorial and testing the finished product, you can get similar results with one coupling and only a few inches of PVC. Other Materials - Black paper with a felt / velvety covering which you can get at Michaels or Hobby Lobby for cheap. Typically it's found near the mat cutting section. I actually already had some laying around. Flat black spray paint. Tools Something to cut the PVC pipe, I used a hacksaw.
A flat head screwdriver.
A dremel or some kind of cutting device (or torch it like I did).
Sandpaper.
Tape measurer or ruler.

Instructions

Cut the PVC - I placed the PVC in a vice grip and used a hack saw. Cut the first piece to 6 inches. Again, I also tried the lens without this 6 inch piece and was pleased with the results. You can see the diagram below to see what I'm talking about. Sand and spray the inside - This isn't totally necessary but I'd do it if I were you. If you've ever worked with PVC you know how it carries a lot of static electricity. Sanding, cleaning and painting the PVC really cut down on a lot of the dust that the piece will be allowed to attract.

Tip: After you sand and before you paint, use rubbing alcohol to clean the inside.


Do the same steps above using a 2 inch piece - Make sure to tape one of the ends completely so you don't spray where you're going to glue.
Tip: Use the factory cut side to glue. This way you know you're going to get a good seal.

Cut the adaptor - This is the piece that protects your camera innards while the lens is not mounted.


Cut along the inner circle. I didn't have any spare dremel bits so I used a propane torch and a piece of scrap metal and cut it like buttah. It was messy and it smelled bad so I'd recommend getting a bit for your dremel.

Sand the piece down smooth and clean it with alcohol to prep it for the epoxy.
Glue it -

Piece it together -


Stopping here (the next photo) would be totally cool. I did test the lens in the end of the coupling you see below and actually preferred the shorter extension.

Roll the Paper -


Put the lens in -




The end of the lens fits quite nicely into the rubber coupling. You shouldn't need to use the clamp but it's there if you need it. Essentially the rubber coupling allows the lens to be reversed, that's where the 'reverse ring' comes in. The coupling and the pvc extension holds the lens further away from the camera, which is where the magnification comes in. ALSO, you still have full control over the focus. This is especially nice when you finally get everything lined up and it's just a touch out of focus, now you can make minor adjustments without moving the lens or the subject. Here is a rough diagram to show the assembly with the two different set ups (Long and Short).

Finishing up - So if you want to go for the shorter extension, you're looking at around $5-$10 cost for this nice addition. The longer extension will cost you another coupling which is approx $3.

The setup

Examples

I wish I had more to show but I didn't really use this a lot. This is a shot I did of my ring. The first example is with a standard 18-55mm lens. The second is with the reverse macro ring.